Case Study to Investigate Pathogenic Microbes and Organic Materials in an Endoscope Washer Disinfector and its Treatment Using a Novel Remediation Technology

Miss Candice Tolton1, Mr Stephen Adnams2

1Tristel Solutions Ltd., Newmarket, United Kingdom, 2Tristel Solutions Ltd., Victoria, Australia

Introduction: Endoscopy procedures are routinely carried out using specific endoscopes in various areas of the body. This is an invasive diagnostic method, where devices are in contact with internal cavities of the patient. It is crucial these devices are thoroughly disinfected and subsequently rinsed with microbe-free water, to prevent the re-contamination and subsequent spread of infectious diseases. One of the most common methods for endoscope reprocessing is through an endoscope washer-disinfector (EWD).

A case study in Tamworth (AU) sought to apply an inline water treatment system utilising filtration and chlorine dioxide (ClO₂) to an EWD removed from service, due to severe microbial contamination.

Method:  Five 500mL water samples from the EWD were taken at different stages to analyse contaminants before, during, and after implementing the water treatment system.  Chemical purity was assessed in addition to microbial analysis, including total viable counts (TVC’s), Pseudomonas, Mycobacteria and endotoxin levels.

Results: A total reduction in TVC’s (<1CFU/100mL) was shown following treatment as opposed to water from the EWD prior to treatment (>100CFU/100mL). No Pseudomonas or Mycobacteria were detected pre- or post-treatment. Endotoxins were also reduced with ClO₂ chemistry (1.6 EU/mL vs. 21.5 EU/mL). Chemical purity was also improved post-treatment. Both chemical purity and microbial counts met the requirements of EWD regulations EN 15883 and AS/NZS 4187.

Conclusion: Water treatment comprising filtration and ClO₂ can rectify an out of service EWD, providing an extensive reduction of microbial contamination and greater chemical purity, whilst achieving compliance with applicable standards


Stephen is from the UK and completed his engineering apprenticeship in the Royal Navy as a Weapons Engineer.  In 2012, Stephen emigrated to Australia, where he took the role of Field Service Engineer with Laboratory Analysers Australia, a company that specialises in Analytical Instrumentation to the mining industry.

In 2015, Stephen returned to the UK and commenced in the role of Resident Maintenance Manager with S.S.I Schaefer. April 2017, Stephen was appointed as the Service Manager with T.E.S.T Ltd., where he focused on Water Quality within Endoscopy Units, leading to an expert understanding of the challenges and potential solutions available to Hospitals. His knowledge has been relied on to ensure water quality met international and local Standards.

Stephen’s knowledge has led to him returning to Australia Tristel, where he works with facilities to evaluate their endoscopy water quality and implement solutions to ensure full compliance with the ASNZ 4187 Standards.

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